Methods for forming a high contrast image by using hydrazine derivatives are well known and have been widely used for a photomechanical process. However, the developers used for the process generally require high pH and therefore are easily subjected to aerial oxidation, which causes the developers to be unstabilized.
Attempts have been made to develop silver halide photographic materials containing hydrazine compounds with developers of lower pH to form a high contrast image.
A process for developing a sensitive material which contains a nucleating accelerator having an adsorbing group for silver halide emulsion grains and simultaneously a nucleating agent having an adsorbing group with a developer having a pH of 11.0 or lower is described in JP-A-1-179939 (The term "JP-A" as used herein means an "unexamined published Japanese patent application") and JP-A-1-179940. However, when the adsorbing group-containing compounds exceeding a certain amount are added to a silver halide emulsion, the compounds have the disadvantage of deteriorating the photosensitivity, of controlling development, and of preventing the effects of other useful adsorbent additives. The usage of the compounds is therefore limited, thus failing to produce sufficiently high contrast.
U.S. Pat. Nos. 4,998,604 and 4,994,365 have disclosed a hydrazine compound having a repeating unit of ethylene oxide and a hydrazine compound having a pyridinium group. However, as is apparent from the examples of these patents, the resulting sensitive materials are difficult to afford sufficiently high contrast property and desired D.sub.max under the practical conditions of development.
Further, nucleating high contrast sensitive materials containing hydrazine compounds have wide variation in photographic properties with change in pH of a developer. The pH of developers largely changes, because the pH increases by aerial oxidation and concentration of the developers owing to evaporation of water, or decreases by absorption of carbon dioxide in air. Hence, attempts have been made to reduce the dependence of photographic performance upon the pH of developers.
As mentioned above, in the prior art, sensitive materials having sufficiently high contrast and little dependence of photographic performance on the pH of the developers cannot be obtained even if the materials are processed with developers having a pH of less than 11.
Sensitive materials containing hydrazine derivatives and reductones are disclosed in JP-B-6-68615 (The term "JP-B" as herein means an "examined Japanese patent publication") The developers contain dihydroxybenzenes, 3-pyrazolidones and aminophenols and are adjusted to pH 10.5 to pH 12.3. However, in this method for forming an image, high contrast although the reductones had a preventive action on generation of black peppers, acceleration of increase of contrast could not be obtained even if the reductones was used.